The UK's major banks are being told to step up their efforts to raise capital by a new Bank of England regulatory body which is concerned they are not holding enough to "ensure resilience in the face of the prospective risks".

The FPC, set up by the coalition to tackle systemic risks in the financial system, also attracted criticism from Andrew Tyrie, the chair of the Treasury select committee, for failing to explain why it was not going to ask the government for powers to intervene in the mortgage market.

The FPC did not detail how much more capital banks would need and it will now fall to the Financial Services Authority to have discussions with individual banks about their capital positions. All them are holding capital well above the minimum regulatory requirements, but the FPC is more concerned about absolute capital levels than the ratio of capital to its risks.

The last time the FPC made pronouncements after its quarterly meetings it warned of the "exceptionally threatening environment" posed by the eurozone crisis and need to restrict bonuses and dividends to amass capital.

The FPC said on Friday that the FSA had then discussed with banks how they could build capital in the short term. "Some progress has been made by banks in meeting the committee's recommendation," the FPC said, with cash bonuses down at four of the five largest UK banks and 17% down in total. Total capital at the three largest banks without taxpayer bailouts (while not named by the FPC these are Barclays, HSBC and Standard Chartered) has increased by more than £1.5bn in the second half of 2011.

"Nevertheless, the committee remained concerned that capital was not yet at levels that would ensure resilience in the face of the prospective risks. It therefore agreed on the need for banks to continue to restrain cash distributions, including via share buybacks. But the scope to build capital through this route was limited. It therefore advised banks to raise external capital as early as feasible," the FPC said. Three months ago it said banks should give "serious consideration" to raising capital.

The members of the FPC, led by Bank of England governor Sir Mervyn King, agreed that financial markets but were still "fragile", even with the European Central Bank's long-term financial operations. "Banks with large exposures to those countries where risks of persistent low economic growth and potential credit defaults remained high should be particularly alert to the need to build capital," the FPC said.

The committee, which will not get statutory powers until next year, wants to be able to impose additional capital requirements on banks through what are known as "counter cyclical buffers" that can then be drawn down when the economy weakens. But the FPC called for a wider debate about whether it should be allowed to intervene in the mortgage market to restrict the size of loans to the value of a home or the size of the loan according to the homebuyer's income.

"While recognising the potential power of these instruments, the committee also noted that the use of these tools would require a high level of public acceptability," the FPC said. This infuriated Tyrie. "The FPC's decision not to ask for stronger tools appears to demonstrate clearly that they lack the confidence, at this time, to explain to the wider public why such tools are necessary," the MP said.